1. Field of the Invention
The present invention relates to a semiconductor device including a resistance voltage divider circuit that divides voltages using resistors and is used for detecting an output voltage of a constant voltage circuit for a whole category of electronic equipment high precision protectors for cell phones and other devices that use on-board Li+/Li polymer batteries, and more particularly, a semiconductor device including a resistance voltage divider circuit that is equipped with trimming resistors.
2. Discussion of the Background
In order to output a divided voltage accurately, in a resistance divider voltage circuit used for detecting an output voltage of a constant voltage circuit it is important that precision of resistance ratio of resistors forming the voltage divider circuit be higher than that of an absolute resistance value.
In general, resistors formed in semiconductor devices do not necessarily have an identical resistance value even though they have an identical configuration, due to variations in manufacturing processes when they are positioned separately in the semiconductor chip. Further, the resistance value of the resistors formed in the semiconductor device can also vary because they can receive stress differently during the molding process.
Therefore, the resistors used in the voltage divider circuit are usually formed in groups in a resistance layout area in the semiconductor device. However, those resistance values can vary depending on location, such as a center portion, end portions, and boundary portions, even though the resistors have an identical configuration.
In order to solve the problem described above, in one known configuration each resistance element forming a voltage divider circuit is divided into multiple unit resistors, and the unit resistors belonging to one resistance element are alternated with unit resistors belonging to another resistance element.
However, in the above-mentioned configuration, wiring is complicated since the unit resistors belonging to one resistance element are arranged alternately with the unit resistors belonging to another resistance element.
As an additional complication, because the number of the unit resistors in each resistance element needs to be the same or substantially the same, some problems arise. For example, the number of the unit resistors can be increased, and accordingly the resistance layout area can be larger, and, if the resistance values of the resistance elements are extremely different, the unit resistors thereof cannot be arranged alternately.
Moreover, because resistance elements that require high-precision are arranged alternately with resistance elements that do not require high precision, when the resistance elements forming the voltage divider circuit increase in number, improving the precision of the resistance elements that require high precision is difficult.
In another known configuration, among resistors forming a divider circuit, multiple resistors that require relatively high precision are arranged adjacently in a center portion of a layout area, and other resistors are arranged outside those resistors.
However, although the resistors can be arranged irrespective of the resistance value and wiring is simple, a precision of the resistance ratio is lower than the former configuration.